/**
 * Copyright (C) 2002-2015   The FreeCol Team
 * <p>
 * This file is part of FreeCol.
 * <p>
 * FreeCol is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 * <p>
 * FreeCol is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * <p>
 * You should have received a copy of the GNU General Public License
 * along with FreeCol.  If not, see <http://www.gnu.org/licenses/>.
 */

package net.sf.freecol.server.ai.mission;

import java.util.logging.Logger;

import javax.xml.stream.XMLStreamException;

import net.sf.freecol.common.io.FreeColXMLReader;
import net.sf.freecol.common.io.FreeColXMLWriter;
import net.sf.freecol.common.model.Colony;
import net.sf.freecol.common.model.Location;
import net.sf.freecol.common.model.pathfinding.CostDeciders;
import net.sf.freecol.common.model.Unit;
import net.sf.freecol.common.util.LogBuilder;
import net.sf.freecol.server.ai.AIColony;
import net.sf.freecol.server.ai.AIMain;
import net.sf.freecol.server.ai.AIUnit;


/**
 * Mission for working inside an AI colony.
 */
public class WorkInsideColonyMission extends Mission
{

    private static final Logger logger = Logger.getLogger( WorkInsideColonyMission.class.getName( ) );

    /** The tag for this mission. */
    private static final String tag = "AI worker";

    /** The target colony to work inside. */
    private Colony colony;


    /**
     * Creates a mission for the given <code>AIUnit</code>.
     *
     * @param aiMain The main AI-object.
     * @param aiUnit The <code>AIUnit</code> this mission is created for.
     * @param aiColony The <code>AIColony</code> the unit should be
     *     working in.
     */
    public WorkInsideColonyMission( AIMain aiMain, AIUnit aiUnit,
                                    AIColony aiColony )
    {
        super( aiMain, aiUnit, aiColony.getColony( ) );
    }

    /**
     * Creates a new <code>WorkInsideColonyMission</code> and reads
     * the given element.
     *
     * @param aiMain The main AI-object.
     * @param aiUnit The <code>AIUnit</code> this mission is created for.
     * @param xr The input stream containing the XML.
     * @throws XMLStreamException if a problem was encountered
     *      during parsing.
     * @see net.sf.freecol.server.ai.AIObject#readFromXML
     */
    public WorkInsideColonyMission( AIMain aiMain, AIUnit aiUnit,
                                    FreeColXMLReader xr ) throws XMLStreamException
    {
        super( aiMain, aiUnit );

        readFromXML( xr );
    }


    /**
     * Convenience accessor for the colony to work in.
     *
     * @return The <code>AIColony</code> to work in.
     */
    public AIColony getAIColony( )
    {
        return getAIMain( ).getAIColony( colony );
    }

    /**
     * Why would this mission be invalid with the given AI unit and location?
     *
     * @param aiUnit The <code>AIUnit</code> to check.
     * @param loc The <code>Location</code> to check.
     * @return A reason for invalidity, or null if none found.
     */
    public static String invalidReason( AIUnit aiUnit, Location loc )
    {
        String reason;
        return ( ( reason = invalidAIUnitReason( aiUnit ) ) != null ) ? reason
                : ( ! aiUnit.getUnit( ).isPerson( ) ) ? Mission.UNITNOTAPERSON
                : ( ( reason = invalidTargetReason( loc, aiUnit.getUnit( ).getOwner( ) ) )
                != null ) ? reason
                : null;
    }


    // Implement Mission
    //   Inherit dispose, getTransportDestination, isOneTime

    /**
     * {@inheritDoc}
     */
    @Override
    public int getBaseTransportPriority( )
    {
        return NORMAL_TRANSPORT_PRIORITY;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public Location getTarget( )
    {
        return colony;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void setTarget( Location target )
    {
        if ( target instanceof Colony )
        {
            this.colony = ( Colony ) target;
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public Location findTarget( )
    {
        return getTarget( );
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String invalidReason( )
    {
        return invalidReason( getAIUnit( ), getTarget( ) );
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public Mission doMission( LogBuilder lb )
    {
        lb.add( tag );
        String reason = invalidReason( );
        if ( reason != null ) return lbFail( lb, false, reason );

        final Unit unit = getUnit( );
        Unit.MoveType mt = travelToTarget( getTarget( ),
                                           CostDeciders.avoidSettlementsAndBlockingUnits( ), lb );
        switch ( mt )
        {
            case MOVE: // Arrived
                break;

            case MOVE_HIGH_SEAS:
            case MOVE_NO_REPAIR:
            case MOVE_NO_MOVES:
            case MOVE_ILLEGAL:
                return lbWait( lb );

            case MOVE_NO_ACCESS_EMBARK:
            case MOVE_NO_TILE:
                return this;

            default:
                return lbMove( lb, mt );
        }

        lbAt( lb );
        if ( unit.isInColony( ) ) lb.add( ", working" );
        return lbWait( lb );
    }


    // Serialization

    private static final String COLONY_TAG = "colony";


    /**
     * {@inheritDoc}
     */
    @Override
    protected void writeAttributes( FreeColXMLWriter xw ) throws XMLStreamException
    {
        super.writeAttributes( xw );

        xw.writeAttribute( COLONY_TAG, colony );
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected void readAttributes( FreeColXMLReader xr ) throws XMLStreamException
    {
        super.readAttributes( xr );

        colony = xr.getAttribute( getGame( ), COLONY_TAG,
                                  Colony.class, ( Colony ) null );
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String getXMLTagName( ) { return getXMLElementTagName( ); }

    /**
     * Gets the tag name of the root element representing this object.
     *
     * @return "workInsideColonyMission".
     */
    public static String getXMLElementTagName( )
    {
        return "workInsideColonyMission";
    }
}
